Version: (using KDE 4.1.3) OS: Linux Installed from: Ubuntu Packages So when changing screen resolution via Display tab in System Settings you can't revert to your previous settings in case something goes wrong. This is a rather new KDE install done via normal Ubuntu package handling methods (Istalled kubuntu-desktop so this probably affects kubuntu distro also). I'm using a laptop with an external screen in clone mode, haven't tested does this happen when using only the laptop's screen. The resolution itself changes just fine so it's only this revert issue.
*** This bug has been marked as a duplicate of bug 222110 ***